<template>
  <div class="pagination">
    <button :disabled="pageNo === 1" @click="$emit('getPageNo', pageNo - 1)"><i class="iconfont icon-zuojiantou"></i>上一页</button>
    <button v-if="startAndEnd.start > 1" @click="$emit('getPageNo', pageNo === 1)" :class="{ active: pageNo === 1 }">1</button>
    <button v-if="startAndEnd.start > 2">···</button>
    <!-- eslint-disable-next-line vue/no-use-v-if-with-v-for -->
    <button v-for="(page, index) in startAndEnd.end" :key="index" v-if="page >= startAndEnd.start" @click="$emit('getPageNo', page)" :class="{ active: pageNo === page }">{{ page }}</button>
    <button v-if="startAndEnd.end < totalPage - 1">···</button>
    <button v-if="startAndEnd.end < totalPage" @click="$emit('getPageNo', totalPage)" :class="{ active: pageNo === totalPage }">{{ totalPage }}</button>
    <button :disabled="pageNo === totalPage" @click="$emit('getPageNo', pageNo + 1)">下一页<i class="iconfont icon-arrow-right"></i></button>

    <button style="margin-left: 30px">共 {{ total }} 条</button>
  </div>
</template>

<script>
export default {
  name: 'Pagination',
  props: ['pageNo', 'pageSize', 'total', 'continues'],
  computed: {
    // 计算出总共多少页
    totalPage() {
      return Math.ceil(this.total / this.pageSize)
    },
    // 计算出连续页码的起始数字
    startAndEnd() {
      // 结构出props里的数据和totalPage，使用时不用加this
      const { totalPage, pageNo, continues } = this
      let start = 0
      let end = 0

      // 先判断连续的页数是否大于总页数
      if (continues > totalPage) {
        start = 1
        end = totalPage
      } else {
        start = pageNo - parseInt(continues / 2)
        end = pageNo + parseInt(continues / 2)
        // 判断第一页是否小于1
        if (start < 1) {
          start = 1
          end = continues
        }
        // 判断尾页是否大于总页数
        if (end > totalPage) {
          end = totalPage
          start = totalPage - continues + 1
        }
      }
      return { start, end }
    }
  }
}
</script>

<style lang="less" scoped>
.pagination {
  text-align: center;
  button {
    margin: 0 5px;
    background-color: #f4f4f5;
    color: #606266;
    outline: none;
    border-radius: 2px;
    padding: 0 4px;
    vertical-align: top;
    display: inline-block;
    font-size: 13px;
    min-width: 35.5px;
    height: 28px;
    line-height: 28px;
    cursor: pointer;
    box-sizing: border-box;
    text-align: center;
    border: 0;
    .iconfont {
      font-size: 10px;
    }
    &[disabled] {
      color: #c0c4cc;
      cursor: not-allowed;
    }

    &.active {
      cursor: not-allowed;
      background-color: #409eff;
      color: #fff;
    }
  }
  button:hover {
    border: 1px solid skyblue;
  }
}
</style>
